| 摘要 |
PURPOSE:To make a titlted filter small-sized and stable, by forming plural filter elments as one body by etching from one piezoelectric plate, and coupling the capacity between the filter elements, by the part of the piezoelectric plate for connecting each element. CONSTITUTION:With regard to a crystal plate 60, its unnecessary part is removed so that 2 pieces of prescribed monolithic filter elements corresponding to a frequency characteristic of a filter can be obtained. Subsequently, a pattern 40' for realizing an input electrode 11, and output electrode 22, and the coupled capacity is vapor-deposited to the substrate part for connecting the element, on the surface side. Also, onto the reverse side,an earth electrode 33' is vapor-deposited. Subsequently, the electrode 11 and an input terminal 10, the electrode 22 and an output terminal 20, and the earth electrodes 33', 33'' and an earth terminal 30 are connected by a lead wire, rspectively. By the pattern 40', the capacity coupling is realized, and in case of adjusting the band width, it can be executed by trimming the pattern 40'. |
